Stable polymorphic compositions of brequinar sodium and methods of use and manufacture thereof

A method of making a crystal comprising at least 80% polymorphic form C of brequinar sodium salt, the method comprising the steps of:

• combining a solid form of brequinar acid, sodium hydroxide (NaOH), and a solvent comprising isopropanol and water to produce a solution and removing insoluble material from the combined brequinar acid, NaOH, and solvent;
• crystallizing brequinar sodium salt from the solution to produce a crystal comprising polymorphic form C of brequinar sodium salt, wherein the crystallizing step comprises sequentially performing the steps of:
• adding a seed crystal of polymorphic form C of brequinar sodium salt to the solution to produce a seeded mixture;
• adding n-heptane to the seeded mixture to produce an alkane-containing mixture and incubating the alkane-containing mixture at from about 15° C. to about 35° C.;
• and
• removing the solvent from the seeded mixture at a temperature below ambient temperatures, wherein the removing step results in a crystal comprising at least 80% polymorphic form C of brequinar sodium salt as measured by X-ray Diffraction (XRD).